Team:Wageningen UR/Project/ProtocolsProj1

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Building a Synchronized Oscillatory System

Main Project

Protocols

Media

LB

Ingredients:

10 g Bacto-tryptone

5 g yeast extract

10 g NaCl


SOB

Ingredients

0.5% (w/v) yeast extract

2% (w/v) tryptone

10 mM NaCl

2.5 mM KCl

20 mM MgSO4

Per liter

5 g yeast extract

20 g tryptone

0.584 g NaCl

0.186 g KCl

2.4 g MgSO4


SOC

Ingredients

SOB

20 mM glucose


CCMB80 buffer for preparation of chemically competent cells


Materials

Detergent-free, sterile glassware and plasticware

Table-top OD600nm spectrophotometer

SOB


CCMB80 buffer


10 mM KOAc pH 7.0 (10 ml of a 1M stock/L)

80 mM CaCl2.2H2O (11.8 g/L)

20 mM MnCl2.4H2O (4.0 g/L)

10 mM MgCl2.6H2O (2.0 g/L)

10% glycerol (100 ml/L)

Adjust pH DOWN to 6.4 with 0.1N HCl if necessary

Adjusting pH up will precipitate manganese dioxide from Mn containing solutions

Filter sterilize and store at 4°C

Slight dark precipitate appears not to affect its function

Procedures

Preparation of chemically competent cells

Preparing glassware and media


Detergent is a major inhibitor of competent cell growth and transformation. Glass and plastic must be detergent free for these protocols. The easiest way to do this is to avoid washing glassware, and simply rinse it out. Autoclaving glassware filled 3/4 with DI water is an effective way to remove most detergent residue. Media and buffers should be prepared in detergent free glassware and cultures grown up in detergent free glassware.

Prechill plasticware and glassware

Prechill 250mL centrifuge tubes and screw cap tubes before use.

Preparing seed stocks

Streak TOP10 cells on an SOB plate and grow for single colonies at 23°C works well. Pick single colonies into 2 ml of SOB medium and shake overnight at 23°C. Add glycerol to 15% and aliquot 1 ml samples into cryotubes. Place tubes into a zip lock bag, immerse bag into a dry ice/ethanol bath for 5 minutes. Place in -80°C freezer indefinitely.Preparing competent cells. Inoculate 250 ml of SOB medium with 1 ml vial of seed stock and grow at 20°C to an OD600nm of 0.3. This takes approximately 16 hours.

Preparing competent cells

Aim for lower, not higher OD if you can't hit this mark.Centrifuge at 3000g at 4°C for 10 minutes in a flat bottom centrifuge bottle.Gently resuspend in 80 ml of ice cold CCMB80 buffer. Incubate on ice 20 minutes, centrifuge again at 4°C and resuspend in 10 ml of ice cold CCMB80 buffer.Test OD of a mixture of 200 μl SOC and 50 μl of the resuspended cells. Add chilled CCMB80 to yield a final OD of 1.0-1.5 in this test. Incubate on ice for 20 minutes. Aliquot to chilled screw top 2 ml vials or 50 μl into chilled microtiter plates. Store at -80°C indefinitely

Test competence (see below)

Do not thaw and refreeze, as this dramatically decreases the transformation efficiency.

Transform 50 μl of cells with 1 μl of standard pUC19 plasmid. Use a 10 pg/μl stock. Hold on ice 0.5 hours. Heat shock 60 sec at 42C and add 250 μl SOC.

Incubate at 37 C for 1 hour in 2 ml centrifuge tubes under rotation.

To increase yields, an incubation time of 2 hours can be used. Plate 20 μl on AMP plates. Good cells should yield around 100 - 400 colonies. Transformation efficiency is (dilution factor=15) x colony count x 105/µg DNA. The transformation efficiency should be between 5x10^8 and 5x10^9 cfu/µg DNA.


5x Ligation Adjustment Buffer

Intended to be mixed with ligation reactions to adjust buffer composition to be near

the CCMB80 buffer

KOAc 40 mM (40 ml/liter of 1 M KOAc solution, pH 7.0)

CaCl2 400 mM (200 ml/l of a 2 M solution)

MnCl2 100 mM (100 ml/l of a 1 M solution)

Glycerol 46.8% (468 ml/liter)

pH adjustment with 2.3% of a 10% acetic acid solution (12.8ml/liter)

Previous protocol indicated amount of acetic acid added should be 23 ml/liter but

that amount was found to be 2X too much per tests on 1.23.07 --Meaganl 15:50,

25 January 2007 (EST)

water to 1 liter

autoclave or sterile filter

Test pH adjustment by mixing 4 parts ligation buffer + 1 part 5x ligation adjustment

buffer and checking pH to be 6.3 - 6.5